1. Field of the Invention
The present invention relates to a measuring instrument. Particularly, the present invention relates to a measuring instrument that includes a plurality of assemblies, at least one assembly of which serves as a movable member or a guide member for supporting a movement of the movable member.
2. Description of Related Art
Conventionally, a coordinate measuring machine for measuring three dimensional data such as dimension and profile of a workpiece has been known (for example, see JP2000-65561A). In the above coordinate measuring machine, a probe and a table can relatively be moved in three axial-directions of X, Y and Z-axis directions being orthogonal each other to measure the three dimensional data such as the dimension and the profile of the workpiece based on a movement displacement amount of each axis when the probe contacts the workpiece set on the table.
Currently, the above coordinate measuring machine has been highly improved in measuring speed and measuring accuracy. However, with the measuring speed and the measuring accuracy highly improved, vibration generated when the probe and the table are relatively moved cannot be ignored. As a vibration attenuation mechanism for such vibration, a mechanism that actively attenuates the vibration by an elastic rubber or a spring etc. provided on a body of the coordinate measuring machine has been employed.
However, the vibration attenuation mechanism has the limitation of attenuating the vibration. Accordingly, a new method for attenuating the vibration has been desired in order to further highly improve speed and accuracy of the coordinate measuring machine.
Incidentally, a casting member having a rib therein is used for a guide that guides movement of the probe and for a table on which the workpiece is set, in order to secure rigidity and secular stability. When such casting member is cast, since the rib is formed with the use of a core, an opening is necessary to be provided on the casting member for removing core sand used at the casting, and the core sand is necessary to be removed from the casting member. Thus, there has been a disadvantage that the casting of the guide and the table need numerous steps, thus not efficiently producing the casting member.